August 2010 Archive for Dairy Today Healthline

Some long-standing perceptions about cattle vaccines are becoming more outdated with each passing day. For instance, over time producers have been conditioned to believe that modified-live vaccines provide a stronger cell-mediated immune response than inactivated, or killed vaccines. This commonly held belief among many dairy industry professionals dates all the way back to the 1980’s, perhaps even earlier.

There was a period of time when that may have been true. But it’s certainly not the case with the leading inactivated cattle vaccine producers are using today. While 1990 doesn’t seem like a long time ago for those of us graying at the temples, it may as well represent the Dark Ages when it comes to vaccine technology.

In the medical research and scientific communities,the knowledge base on immunology is doubling every three to five years. As a result, the vaccines we’re using today are much more sophisticated than they were as recently as the 1990s.

Advances in viral immunology and how vaccines work to prevent common cattle diseases like BVD may often start with human medicine. New, improved technologies and adjuvants used in human vaccines can be quickly applied to animal vaccines. And that’s true for vaccines used in cattle and other production livestock animals.

What hasn’t kept pace with advances in viral immunology, however, is communication with producers to explain how modern vaccines have changed and work to prevent cattle diseases. Consequently, some of these long-held misconceptions still linger, despite recent evidence that proves they are outdated and no longer accurate.

Take the case of inactivated vaccines and cell-mediated immunity; several studies have shown that properly adjuvanted inactivated products do produce a complete response, which means they invoke both a humoral and a cell-mediated immune response. Cell-mediated immunity is important because it provides valuable defense against invading pathogens, like the virus that causes BVD.

One of the more recent studies was published in the peer-reviewed journal Veterinary Therapeutics. Specifically, this study evaluated an inactivated vaccine’s ability to produce a cell-mediated immune response to BVD. And the results were very conclusive. The inactivated vaccine tested provided a strong cell-mediated immune response, as well as a humoral response to provide complete protection from BVD.

Other studies have shown that some inactivated vaccines can actually induce a stronger cell-mediated immune response than modified-live vaccines.

A study conducted at Iowa State University that found an adjuvanted, inactivated vaccine provided a much stronger cell-mediated immune response to BRSV than the modified-live vaccine it was compared to. This study suggests the inactivated vaccine would provide a better protective response, although a challenge was not preformed.

Technology has led to some significant changes since the 1990s when few, if any of us, had cell phones, GPS systems or digital cameras. Today these things are as common as flies in summer. Vaccine technology has advanced at an equally rapid pace, calling into question many long-held beliefs.